To prevent a lowering of strength of a furnace body in high temperatures.

The furnace body 1 of this dry distillation furnace for induction heating by a heating coil 2 is formed in double structure comprising an inner furnace made of a nonmagnetic material, and an outer furnace 10 made of a magnetic material. The inner furnace 9 is structurally held by the outer furnace 10 through spacers 12, 13. The inner furnace 9 functions as a heating body, and the outer furnace 10 functions as a structural member for holding the inner furnace 9. As a result, the inner furnace 9 is prevented from crack initiation, distortion, or the like regardless of a lowering of mechanical strength caused by a high temperature, and in the outer furnace 10, an induction current is minimized to reduce heat loss.